This invention relates to a looper for the manufacture of tufted carpets on tufting machines.
As already known, the tufts on tufted carpets are formed on a tufting machine by stitching pile yarns into a backing fabric, drawing out the pile yarns by the tips of loopers arranged as opposed to the needles to form loops, and cutting the top of the loops with the blades of the loopers.
For the tufting of a backing fabric as described above, tufting machines are provided with 1,000 to 1,800 pairs of needles and loopers which are arranged side by side and by which a low of tufts is formed instantaneously. This operation is repeated in succession to form tufts over the fabric.
When it becomes necessary to replace and adjust even a single looper among a large number of loopers on the tufting machine, the machine must wholly be brought out of operation and requires about 70 hours in total for the replacement and adjustment before a stable operation is resumed.
Accordingly one skilled in the art makes constant efforts at the maintenance of various parts to assure the proper operation of the tufting machine at all times. However wear on the blades of the loopers inevitably occurs.
As materials for tufts on tufted carpets, wool, acrylic fibers and like materials which are most easy to cut were used in the past. Loopers wholly made of steel as shown in FIGS. 1 and 2 were fully serviceable for such materials.
However, chemical fibers as of polypropylene and nylon which are difficult to cut have been introduced into wide use in recent years. When used for these fibers loopers of the all steel type wear rapidly and require frequent replacement. This is seriously disadvantageous for the stable operation of the tufting machine as stated above, greatly reducing the operation efficiency of the machine.
It has therefore been strongly desired to provide a looper having increased resistance to wear and a higher cutting ability. Improved loopers available include those having a head portion which is made entirely of cemented carbide alloy as shown in FIGS. 3 and 4 and those incorporating a cemented carbide alloy insert as seen in FIGS. 5 and 6.
The looper of the former type has a head portion 1 made of cemented carbide alloy and attached by silver soldering to a base portion, namely a mounting portion 2 of steel. Whereas this looper is usable for a prolonged period of time even for cutting chemical fibers, the head portion 1 which is made of cemented carbide alloy has no elasticity, tends to break and is liable to separate at the soldered portion 3. Moreover the looper needs an expensive material, is difficult to make and requires skill in handling, hence various drawbacks.
The looper of the latter type has a cemented carbide insert incorporated in part of the head portion 4, namely in a vertical blade portion 5 and a horizontal blade portion 7 except its right end 6. Although the cemented carbide alloy portions 5 and 7 are less susceptible to wear, the mounting portion 8 and head portion 4 which are made of steel wear rapidly where they adjoin the alloy portions, with the resulting drawback that a step 9 as seen in FIG. 7 will be formed during use. The step 9 will engage yarns and produce a flaw in the product, entailing the necessity for the replacement of the looper while the blade is still sharp-edged.